Research from Holland presented at a conference in Brisbane shows driving with a hangover could be just as dangerous as driving while drunk.
Researchers said drivers should be warned that the effects of heavy drinking extend beyond the point when traces of alcohol have disappeared from the blood.
A Dutch study put volunteers through simulated driving tests the night after they consumed about 10 alcoholic drinks.
AAP reports the tests were taken after their blood alcohol concentrations had returned to zero, and the results were compared with how they performed after a night when they did not drink.
The study shows hangovers can significantly increase the number of lapses in attention, and weaving on the road.
"The magnitude of driving impairment is higher than that observed with a blood alcohol concentration of 0.05%, which is the legal limit for driving in many countries," said Dr Joris Verster of Utrecht University.
A smaller UK study has produced similar findings. It showed hungover drivers are more likely to travel at an inconsistent speed, make more driving errors and weave on the road. They also have slower reaction times.
The hangover study is being presented at the Australasian Professional Society on Alcohol and other Drugs conference in Brisbane.
